Arcadian Functor

occasional meanderings in physics' brave new world

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Marni D. Sheppeard

Friday, May 15, 2009

Force of Gravity

Congratulations to Carl Brannen for winning an honourable mention in the prestigious Gravity Research Foundation essay contest, with a paper entitled The Force of Gravity in Schwarzschild and Gullstrand-Painleve Coordinates. And good luck with the publishing ... hmmm.

Of course even I shudder automatically at the idea of gravity as a Force, but that is why this work is a perfect example of the triumph of pragmatism over obtuse abstraction, a philosophical subject that will be discussed in an interesting seminar here this afternoon by Harvey Brown. In the end, it's the job of a physicist to make things straightforward, and the picture of graviton exchange is something that any schoolkid could understand.

10 Comments:

Blogger CarlBrannen said...

Marni, I think the reason we work well together (i.e. MNS and CKM) is the combination of pragmatism and abstraction.

I wonder what it would be like if I could understand 75% of what you write rather than the current level of around 33%. I'm sure there's some gems in there that need faceting.

May 15, 2009 9:21 PM  
Blogger L. Riofrio said...

Congratulations to Carl! This gives hope to all of us.

May 16, 2009 1:17 AM  
Blogger CarlBrannen said...

The thing about most of modern physics is that it's based not on abstraction so much as on symmetry. GR is the most pronounced of this.

One of the odd features of the category approach to QM is that it avoids talking about symmetrization and antisymmetrization. So these sorts of ideas do have a common thread.

May 16, 2009 5:40 PM  
Blogger nige said...

Well done Carl!

May 16, 2009 8:16 PM  
Blogger Kea said...

If they didn't have a common thread, we wouldn't have been talking to each other for years now! And it makes me happy to see a prize committee reward someone who thinks GR is, well, kind of garbage.

May 16, 2009 10:49 PM  
Blogger CarlBrannen said...

Kea, the more I think about it, I think I might have got some cash if I'd just turned in the exact solution to the post Newtonian Expansion instead of going on about what gravity is made of.

By the way, I'm connected to the internet at the University of British Columbia, in Vancouver, Canada. Getting across the border wasn't as bad as I expected. They even let my beat-up teen-aged Mazda Miata across. I'm giving a talk, will mention you as being involved with this project. If you have objections better make them fast; it's in an hour. (From my reading, I understand that it is customary to shave the heads of collaborators. I've already had the operation.)

May 17, 2009 8:16 AM  
Blogger Kea said...

Well, I missed that hour, lol! Anyway, I'm sure the talk went well.

May 17, 2009 9:29 PM  
Blogger antimatter33 said...

GR is NOT "kind of garbage" - this is too false to even refute. Rmn = 0 is a perfectly good equation and perfectly aligned with what is seen.

And GR is not based on symmetry. It is based on a principle that geometry is part of physics - that the stage is part of the play.

I can't believe how much trash is heaped on Einstein by people who have not the faintest idea of what he really did. This goes for the church of the Big Bang and Inflation as much as it does for those who say "GR is garbage". I have worked on this problem for twenty-five years and I can tell you it is not garbage.

I suggest you read Weyl and Cooperstock. And maybe Einstein.

-drl

May 19, 2009 5:29 PM  
Blogger CarlBrannen said...

"perfectly aligned with what is seen" The problem is that it's incompatible with QM, and what's seen is only to first order.

The symmetry principle for GR is "universality of freefall". The basic problem is that symmetry principles are nothing more than sophisticated curve fitting. Any fool can take a set of experimental observations, fit a curve to them, call it a "symmetry" or a "principle" and then derive predictions from it.

"It is based on a principle that geometry is part of physics ..." The best definition of the geometry of spacetime is given by quantum mechanics. This is Clifford / geometric algebra and GR does not use it. If you want a theory based on geometry, you can't use the theory to define the geometry. That's circular reasoning. Instead, you must define the theory from something else, and then derive the theory from the geometry. (See my essay for more on this topic.)

"... by people who have not the faintest idea of what he really did." I just picked up an honorable mention at the annual gravitation essay contest. The subject of my essay was a new theory of gravity. You can't do that without knowing the old theory.

"I have worked on this problem for twenty-five years and I can tell you it is not garbage." This is the same thing that the classical mechanics people were saying just before QM and relativity showed that they were inadequate. But classical mechanics still has a wide range of application, soon GR will be obsolete.

May 22, 2009 2:48 PM  
Blogger Kea said...

drl, you must have noticed the connection between your SO(3,3) and twistor geometry. Now imagine working with the more abstract sheaf cohomology of twistor theory (for years and years) and then the more abstract category theory behind it (for years and years) and then finding that this is a lot like quantum mechanics (over years and years). Don't you think that's interesting?

May 22, 2009 8:41 PM  

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